1. Field of the Invention
The invention relates generally to eye protection. In particular, this invention relates to an optical filtering apparatus for protecting the eye against radiation from a laser.
2. Description of the Prior Art
The increasing use of leaser light beams in military and other applications has underscored the need for protective systems and, particularly eye wear for protecting individuals from retinal damage. One method for dealing with this is the individual. However, due to the fact that such goggles or safety glasses filter out a wide range of wavelengths, the outside world tends to undergo drastic coloration when viewed through such a shield. Further, if protection from a number of wavelengths is desired, the use of a multilayer conventional color filter reduces the quality of the system form marginal to unacceptable.
Additionally, while such laser safety eyeglasses or goggles do protect the eye of the user from radiation which essentially comes head on and enters through the protective filters, these safety eyeglasses due leave regions open between the upper edge of the mounting frame and the eyebrows of the user and between the lateral edges of the mounting frame and the temple. When working with a laser beam apparatus, it is quite possible that when the user of such safety eyeglasses drops or rotates the head, laser radiation can gain access to the eye of the user through these unprotected regions causing damage thereto.
An alternative to such conventional color filters is the holographic notch filter. Such notch filters, generally, have the desirable characteristic that upon being exposed with light of a given wavelength, in the proper holographic configuration, a very narrow bandwidth effectively reflective surface (which is optically a diffractive surface) will be formed holographically. This reflective surface or xe2x80x9cnotch filterxe2x80x9d comprises recorded interference patterns in a photosensitive material such as dichromated gelatin. Such a holographically exposed gelatin layer will exhibit reflective properties along a very narrow range of wavelengths substantially identical to the recording wavelengths.
However, a serious limitation of such systems is the fact that dichromated gelatin is not sensitive to the various laser hazard wavelengths against which one desires to protect.
With the-disadvantages inherent in the design of prior art laser protective goggles or safety glasses the present invention was conceived and one of its objects is to provide a laser radiation protection device for the human eye which will not interfere with the forward or peripheral vision of the user.
It is yet another object of the present invention to provide a laser eye protection device which is responsive to a broad range of laser frequencies.
It is a further object of the present invention to provide a laser eye protection device which is relatively simple in design, convenient to wear and which will not interfere with the normal activities of the wearer.
These and other objects of the present invention will become apparent from the following detailed description of the preferred embodiment.
The present invention is a device for protecting the human eye by means of a narrow bandwidth interference filter which filters out one or more specific wavelengths of light emitted in the form of a coherent, concentrated beam that is laser radiation, an image intensifier for amplifying an image passing through the narrow bandwidth filter to an observable light level, and a neutral density filter which reduces image reflected illuminance to avoid detection.